Pump for liquefied gases



April 20, 1948. c. R. ANDERSON PUMP FOR LIQUEFIED GASES Original Filed001x21, 1943 3 sheets-sheet 1 \&

AT TORNEYS Ap'ril 20, 1948. c. R. ANDERSON 2,439,958

PUMP FOR LIQUEFIED GASES Original Filed 001'... 21, 1943 3 Sheets-Sheet2 CARL R. ANDERSON INVEN TOR N wwmm A T' TORNEVS April 1943- c. R.ANDERSON 2,439,958

PUMP FOR LIQUEFIED GASES Original Filed Oct. 21, 1943 3 Sheets-Sheet I5CARL RAND, soN ENTOI? Patented Apr. 2c, 1948 OFFICE rum ron. noun-mpoases Carl R. Anderson, Chattanooga, Tenn, assignor to Air ProductsIncorporated, Chattanooga, Tenn, a corporation of Michigan Originalapplication mm 21, 1943, Serial No.

Divided and this application August 10, 1944, Serial No. 548,846

11 Claims. (01. 103-4) This invention relates to a pump for liquefiedgases.

This invention relates to apparatus for pumping liquefied gases, as forexample liquid air or liquid oxygen, in the liquid condition.

In the preparation and use of certain liquids having extremely lowboiling points at atmospheric pressure it is often highly economical anddesirable to transfer them from one point to another in the liquidrather than in the gaseous condition.

For example, it is now common practice to store liquefied natural gas inlarge quantities, at or near atmospheric pressure, in heavily insulatedtanks. Such liquefied gases have, on occasion, to be transferred at a.controlled rate to a vaporizer wherein they are vaporized andsuper-heated,

under pressure, to a temperature suitable for delivery into adistribution system. The use of a suitable liquid pump, as hereindescribed, is a simple and convenient means for effecting such transfer.

It is also common practice to store oxygen and other so-called permanentgases, in the liquefied form, to transport the liquid through pipelines, and to bring it back to the gaseous condition at the point atwhich it is to be used or placed in pressure cylinders for finaldistribution. Insuch cases the stored liquefied gas is usually at ornear atmospheric pressure while the conditions of use or distributionmay require that the gasefied liquid be at a very high pressure, oftenup to or over 2500 pounds per square inch. In such service it isextremely desirable to apply the finally required pressure to the liquidrather than to a aseous stream, as both the cost of power and the weightof apparatus required in the former case are small fractions of thecorresponding figures in the latter.

In pumping liquids which, at normal atmospheric pressure, boil attemperatures ranging from 50 to 190 below centigrade zero, greatdifficulty is experienced in keeping a pump in operation. At theseextremely low temperatures the heat head between the atmosphere and theliquid stream is so great that even the best of insulation becomesrelatively ineffective. In consequence, some atmospheric heat leaks intothe liquid on the suction side of the pump and,

2 the very act of increasing its pressure and any such liquid leakingback past the discharge valve, into the pump cylinder, may partiallyvaporize under intake stroke conditions, contributing to vapor lock.

Further, the actuating end of the pump, the end to which power isapplied, is almost necessarily in contact with the atmosphere and at atemperature much higher than that of the liquefied gas, the metallicstructure of the pump thus transmitting atmospheric heat to the streambeing pumped.

Finally, because of the impossibility of lubricating the plunger packingadequately, more or less heat is produced by rod friction and added tothe atmospheric heat tending to raise the temperature of the stream atthe suction end of the One remedy for these difficulties is found incooling the liquid stream below its boiling point at the pressureexisting in the pump cylinder during the suction stroke, as describedand claimed in my copending application Serial No. 488,650, filed May27, 1943. Another step to the sameend is to provide a pumping means inwhich the transfer of either atmospheric or frictional heat, by orthrough thepumping apparatus to the liquid,

is reduced to the lowest possible amount. The

present invention is directed to the provision of such a pumping means.

The invention in its preferred form is illustrated in the attacheddrawings and the following description thereof, in which:

Figs. 1-A and 1-3, taken together, show a longitudinal section throughthe complete assembly: in these figures the left end of Fig. 1-A mateswith the right end of Fig. 1--B to show the complete pump.

Fig. 2 is a section taken on the line 2-2 of Fig. 1, showing the coolinggas inlet in section and the pumping cylinder head in elevation.

Fig. 3 is a section through the pumping cylinder as on the line 3-3 ofFig. 1.

Fig. 4 is a section through a thermal break, lantern ring and leaktester, as shown on the line 4-4 of Fig. 1, and

Fig. 5 is a section through a frame extension and a thermal break, as onthe line 5-5 of Fig. 1.

Referring to the drawings, the pump illustrated is of the single actingplunger type, the main working parts being a pump cylinder I0, 3.plunger ll reciprocating therein, inlet and discharge valves l2 and I3,a frame M, a crosshead [5, a connecting rod I6, a crank l1 and anysuitable type of prime mover indicated at l8.

As the types of prime mover and reducing gear by which power is appliedare immaterial to the invention they are not shown in detail. The valvearrangements illustrated are such as would be.

suitable in a pump horizontally disposed and would be somewhat modifiedif a vertical arrangement were preferred.

A head block is fitted to the end of cylinder i0 and non-leakablyattached to the cylinder wall. A sleeve 2| is passed over the head block(which is relieved as at 22, Fig. 2) to provide passage for a coolinggas and carries a flange 23 at its outer end. The sleeve has a sideoutlet 24 for the cooling gas. Between the cylinder and the sleeve isplaced a spiral bailie 25 to cause the gas to take a circuitous coursearound the cylinder and, by increasing its velocity. to increase therate of heat transfer. This bailie is heat-conductively attached to theexterior of the cylinder wall, thus providing an extended heat absorbingand transfer surface. At its inner end the sleeve is made fast to ametallic ring 28 seated against a shoulder 21 on the outer face of thecylinder.

The assembly above described, consisting of elements 2| to 21 inclusive,forms a jacket for eflectively insulating the cylinder against inflow ofatmospheric heat. It is optional and may be omitted if no supply ofcooling gas is available, some other form of insulation beingsubstituted in that case.

Against sleeve ring 26 and fitting the smaller external diameter of thecylinder is placed a thick and relatively rigid disc 30 of a materialhaving a .low order of heat conductivity. for example, about 1 B. t. u.per hour per cubic foot per degree F. or less. Material having thelowest heat conductivity coupled with sumcient strength is, of course,preferable. Suitable materials are hard rubber, Bakelite or othersynthetic resins or very hard woods such as lisnum vitae. Some of thesematerials have heat conductivities as low as it B. t. u. per hour percubic foot per degree F.

This disc is forced against the sleeve ring, which in turn bears againstshoulder 21, by a nut 3|, the threads engaged by this nut extendingbeyond it as at 82. At its outer edge the disc is fastened by bolts 33to a metallic extension piece 34 which in turn is rigidly attached toframe M. This extension piece is relieved as at 35 to permit access tonut 3| without dismounting the cylinder assembly.

A cylinder extension 36 of material of low heat conductivity, as abovedescribed, is screwed onto projecting threads 32 and passes throughframe [4, in which it is free to move longitudinally within a sleeve 31screwed into a collar 38 fixed in the frame M. This sleeve servestosupport and align the cylinder extension 36 while permitting the travelrequired by expansion and contraction of the cylinder and extensionpiece and which follows from temperature changes and stretch under load.It is desirable to place a packing ring 39 at the inner end of thesleeve to prevent the escape of gas through the slip joint between thecylin- .der extension and the sleeve.

Returning now to the end of the cylinder adjacent the valves, a workingbarrel in is permanently fixed in the end of the cylinder, the bore ofthis barrel being accurately centered and aligned with, and affordingsufllcient clearance over, plunger Ii to avoid rubbing contact. Theplunger is held in alignment and centered in the bore by a guide I!which also acts as a spacer to remove the plunger packing to aconsiderable distance from the working barrel and thus provide a zone ofquiescence l I This spacer may be of any desired material capable ofholding the rod in alignment and of taking the end thrust of thepacking. A preferred form is that shown in Fig. 1-B, in which 42 is atube of stainless steel or other metal or alloy of low heat conductivityand 43-43 are bushings of leaded bronze or other metal having a lowcoeflicient of friction with the metal of the plunger. Externally thetube should have a close sliding fit within the cylinder while the boreof each bushing should have a free sliding fit on the plunger. At theend of the guide. against one of the bushings 43, is placed the mainplunger packing 45, which may be of any type adapted to the liquid to bepumped. This packing should bear on the plunger as lightly as isconsistent with tightness against leakage.

On top of the packing and in lieu of the usual follower is placed alantern ring 46 having an internal circumferential channel 48, anexternal circumferential channel 41 and a port or ports 49 connectingthese channels' A radial bore 50 through the material of the disc and atube 51 inserted in this bore permit any liquid or gas which may passthe main packing 45 to escape to the atmosphere. The tube beingexternally in communication with the atmosphere, any liquid passing thepacking is vaporized and, if the end of the tube be immersed in a bodyof liquid, as illustrated at 52, the appearance of a train oi bubblesgives an instant indication of leakage which might not otherwise beobserved.

I: preferred, a frictionless spinner may be placed in a transparentextension of tube ii to indicate visually the rate of gas flow, or asmall gas meter may be substituted for bubbling pct 52 and the packingtightened when the leakage exceeds a permissible rate. It is notessential that the leak tester discharge to the atmosphere: on thecontrary it may communicate with any vessel or conduit in which thepressure is materially below the pressure existing in the pump cylinderduring the discharge stroke.

The plunger packing is tightened b means of a nut 58 threaded ontosleeve 31 and engaging a gland 54 which transmits the pressure to thelantern ring and through it to the packing, by the agency of a spacer55. This element consists of a tube, preferably of stainless steel orother metal or alloy of low heat conductivity, provided at its ends withthrust collars iii-58.

In order to ensure that all leakage through the main packing escapesthrough tube 5|, it is desirable that gland 54 be provided with a boxfor secondary packing 62, which bears against a bushing 5'! lockedwithin gland 64. Packing 62 is adjusted by a threaded gland 58. Thissecondary packing is further desirable as preventing the chilling of theprotruding portion of plunger H by leakage gas and the consequentdeposition of atmospheric moisture or frost at this point.

The plunger II is preferably formed of 18/8 stainless steel or othermetal or alloy of low heat conductivity. It may also and desirably bedrilled out for a portion of its length, as at 6|, to reduce its crosssection and its ability to transfer heat from the warm end to the coldend of the pump.

A convenient means for attaching the plunger to the crosshead I5 isshown in Fig. 1A, in which 58 is a nut threaded onto the end of theplunger and 60 a hollow cap nut engaging the threaded end of thecrosshead. This construction permits the assembly and packing of thepump with the attaching means disconnected, so that the alignment andposition of the plunger are not aflected by the position of thecrosshead. The connection may thus be effected subsequently to theassembling and packing operations.

The pump structure above described has material advantages overconventional plunger pumps in handling liquids of extreme volatility.which boil at Very low temperatures. The more important of theseadvantages are found in th following elements of structure:

1) In the provision of a cold gas jacket surrounding the workingbarrelof the pump, by which the direct flow of heat into the cylinder from thesurrounding atmosphere is prevented.

No matter how effective a static insulation. such as that afforded bycorkor wool, may be. some heat will pass through it. Where the heat headis so great as in the pumping of liquefied gases, this direct heat flowmay be a highly material amount.

The cooling jacket with provision for passing a refrigerating gasthrough it provides dynamic insulation which may be so regulated as toabsorb and carry away a part or all of the heat passing through the massof static insulation surrounding it, according to the temperature andthe flow rate of the gas stream passed through the jacket.

(2) In the insulation of the cylinder from the metal of the frame by theprovision of a substantially non-conductive connecting element such asdisc 30, which reduces to an insignificant value the flow of thecylinder of atmospheric heat taken up by the frame, and'of heatgenerated by friction in the actuating mechanism, while affording asufiiciently rigid support for the cylinder.

(3) In the insulation of the cylinder from the metal of the crossheadand frame by the provision of the substantially non-conductive cylinderextension 35, which prevents heat drawn from the atmosphere or generatedin the actuating mechanism from entering the cylinder by way of thepacking nut and gland.

(4) In reducing the cross-sectional area of the plunger by drilling outas at GI and by the use of a metal or alloy of low heat conductivity forthe plunger.

Because of the substantial insulation ofthe cylinder from the warm endof the pump, the only road by which any material amount of heat mayenter the cold end is along the plunger itself,

6 wall area available for the transfer of heat to the cooling gas in thejacket but also removes the point at which gas may be evolved during thesuc. tion strok to a long distance from the working barrel and thevalves.

Heat produced by packing friction is transmitted to the annular columnof liquid surrounding the plunger from that portion of the length of theplunger which reciprocates into and out of the packing. The plunger ismade from a metal having low heat conductivity, such, e. g., asstainless steel, so as to reduce heat flow along its length to a verysmall factor. During the suction stroke the pressure within the workingbarrel and on the suction valve falls to or even below atmospheric and,lacking any means of restraint, a similar reduction would occur in space4| and the heat available in that portion of the plunger adjacent thepacking would tend to cause evolution of gas within this space andcorrespondingly to reduce the amount of liquid drawn into the workingbarrel.

stroke and at a pressure at which the evolution of gas and theconsequent short-stroking of the therefore, this last provision reducesthe heat inuid at 4|, within the cylinder and between theworking barreland the packing, together with the provision of the cooling jacketsurrounding this liquid body.

Packing friction may be minimized but cannot wholly be avoided. Thisfriction results in heat, generated within the cylinderand which may beremoved only through the cylinder wall.

The provision of this relatively long and narrow jacketed space not onlyincreases the cylinder pump are substantially or, in most cases, whollyavoided.

The concomitant use of the cooling jacket is essential to the'abovefunction as the heat produced by packing friction must be withdrawn atthe same rate as that at which it is generated. The provision of thequiescent liquid body,.restrained from rapid flow into the workingbarrel, permits this heat to be withdrawn at a higher temperature leveland therefore at a more rapid rate.

(6) Inthe interposition of the spacer 55, of low heat conductivity,between the main packing 45 and the gland 54, by which the portion ofthe plunger in contact with the liquid being pumped is removed to aconsiderable distance from the portion of the plunger which comes intocontact with the atmosphere.

('7) In the provision of lantern ring 46 and an 'outlet 50 for theescape of packing leakage; to-

gether with the use of secondary packing 62. This is not merely aconvenient means for momentarily ascertaining the condition of theplunger packing but, and of much greater import, it is a means forreducing packing friction by permitting a relatively light adjustment ofthe main packing.

In a pump of this type, having a rod-like plunger, packing leakage maybe reduced to very low terms by a relatively light compression of asuitable soft packing, but to eliminate leakage It therefore becomesnecessary, in the use of the conventional packing arrangements. tooperate with the packing tight enough to avoid leakage completely, notto save an immaterial loss of gas but rather to prevent the icing of theplunger. Cooling of the plunger even to the point at which atmosphericmoisture is deposited but not frozen is objectionable, as such depositedmoisture is carried back into the gland and later, during periods ofpump shut-down, when packing friction is absent, the part of the plungerwithin the gland may become cold enough to Ireeze this moisture, thuseffectively uniting the plunger and the gland.

In detouring the leakage out of the structure through the lantern ringand vent, and in separating the lantern ring from the secondary packingby spacer 55, that portion of the plunger which works within the mainpacking and which is cold is kept entirely away from contact with theatmosphere and consequently free from any possibility of iceaccumulation, while that portion of the plunger reciprocating within thesecondary packing is maintained at or close to atmospheric temperatureand consequentl :tree from any tendency to condense moisture from theair.

(8) In the provision of a slip Joint between cylinder extension 36 andalignment sleeve 31. The use of materials of very low heat conductivityin the cylinder extension and in disc 30 is one of the most importantfeatures of the invention. These materials, however,are deficient inrigidity and the disc in particular will deflect appreciably unless madeso massive that a material part of its insulating value is lost. Theprovision or the slip joint absorbs all longitudinal movements due todeflection of the disc and to endwise expansion of the cylinderextension under highpressure pumping stresses and thus permits the useof the minimum mass of Bakelite or its equivalent consistent withmaintenance of alignment of cylinder extension, cylinder and plungen,

Pumps constructed according to the principles above set forth haveproven in practice to be completely dependable and have operated overextended periods without icing, short-stroking or gas-locking andwithout mechanical trouble of any character.

From the above it will be seen that the pump herein shown and describedis admirably suited for the pumping of liquid oxygen in accordance withthe method described in my copending application Serial No. 488,650,filed May 27, 1943. In using my pump in the apparatus shown in mycopending application, the pump would preferably be refrigerated by thegaseous product nitrogen from the iractionating tower or column.

This application is a division of application Serial No. 507,091, filedOctober 21, 1943.

Iclaim:

1. In combination with a pump having a cylinder, a plunger reciprocatingtherein and packing surrounding said plunger within said cylinder: meansfor supplying said cylinder with a liquefied gas having an atmosphericpressure boiling point materially below atmospheric temperature; alantern ring within said cylinder on the low pressure side of saidpacking; means communicating with said packing for converting liquidleaking through said packing to the form or an invisible gm, and meanscommunicating with last said means for rendering a flow of saidinvisible gas visually evident.

2. In a pump for highly volatile liquids comprising a cylinder, aplunger reciprocating therein, plunger actuating means and a. block orsolid. heat-insulating material mounted on said cylinder and positioningsaid actuating means; a high pressure packing surrounding said plunger;a low pressure packing surrounding said plunger on the low pressure sideoi said high pressure packing; a lantern ring located between said highpressure and low pressure packings and within said block. and a ventthrough said block comniinunicating with the void space of said lantern8.

3. In a pump for liquefied gases comprising a cylinder located in a coldzone. a plunger reciprocating therein and extending outwardly from saidcylinder into a relatively warm zone. and packing surrounding saidplunger: means for preventing the chilling oi the outer extremity ofsaid plunger by fluid leaking past said packing including an enclosurearound a portion oi. the length of said plunger exceeding the plungerstroke. and a conduit arranged to direct said fluid away from saidenclosure at a point closely adjacent said packing.

4. In a pump for pumping liquefied gases at low subatmospherictemperatures, said pump comprising a cylinder, a packing nut and aplunger reciprocating within said cylinder and extending outwardlythrough said packing nut into a zone of substantially atmospherictemperature: packing surrounding said plunger and adapted to becompressed by said packing nut, means for confining fluid leaking 'pastsaid packing, and means for directing said leakag fluid away from saidplunger at a point closely adjacent said packing, whereby chilling oithe outwardly extending portion 01' said plunger is materially reduced.

5. In a pump for pumping liquefied gases at low subatmospherlctemperatures, said pump comprising a cylinder and a plungerreciprocating therein and extending outwardly from said cylinder into azone warmer than said liquid, primary packing surrounding said plunger:means defining an elongated confined space surrounding said plunger andextending outwardly from the low pressure side oi said packing to adistance exceeding the stroke of said plunger. said defining meansincluding secondary packing closin said space at the end opposite saidprimary packing, a vent for leakage fiuid communicating with said spaceat a point adjacent said primary packing and means for maintaining astatic body of gas in said confined space between said vent and saidsecondary packing.

6. In a pump having a cylinder of uniform diameter supplied with aliquefied gas and operating at a low sub-atmospheric temperature and aplunger reciprocating in said cylinder and extending into a warm zoneand into contact with the ambient atmosphere; means for minimizing thedeposition of atmospheric moisture on the outer end of said plungercomprising: primary plunger packing located at a medial point in thelength of said cylinder; secondary plunger packing located at the end oisaid cylinder and spaced from said primary packing by a distanceexceeding the maximum stroke or said plunger; a leakage vent from saidcylinder to the atmosphere at a point closely adjacent said primarypacking and on the low pressure side thereof; independently operableelements mounted in concentric relation on the warm end of said cylinderfor adjusting the pressures applied to said primary and said secondarypackings.

7. In a pump adapted to the pumping oi liquened gases: a cylinder havingsuction and discharge valves; a plunger reciprocating in said cylinderand packing surrounding said plunger, said plunger being hollow in itsoutwardly extendingportion; a cylinder extension shielding saidoutwardly extending portion from contact with the atmosphere, and a ventfor fluids leaking past said packing, said vent being located adJacentsaid packing and on the low pressure side thereof.

8. In a pump for liquefied gases having a cold end including a pumpingcylinder and plunger packing, a warm end including plunger-actuatingmeans, and a metallic plunger extending from said cold end through saidpacking to said warm end: means for substantially preventing thedeposition or atmospheric moisture on the warm end oi said plungerincluding a tube of thermally insulating material projected from saidcylinder beyond said packing and toward said warm end, said tube beingradially spaced from said plunger and shielding said plunger-fromcontact with the atmosphere.

9. In a pump for liquefied gases having a cold end including a pumpingcylinder and plunger packing, a warm end including plunger-actuatingmeans, and a metallic plunger extending through said packing from saidcold end to said warm end: means for substantially preventing thedeposition of atmospheric moisture on the warm end of said Plungerincluding an extension of said cylinder projected for a materialdistance beyond said packing toward said actuating means and in radiallyspaced relation to said plunger; a stationary closure at the warm and ofsaid extension through which said plunger passes, said extension andclosure shielding said plunger from contact with the atmosphere, andmeans for directing packing leakage away from said lunger at the coldend of said cylinder extension.

10. In a pump for liquefied gases having a, cold end including a pumpingcylinder and a high pressure plunger packing, a warm end includingplunger actuating means, and a, reciprocating plunger extending fromsaid cold end through said packing to said warm end: means forsubstantially preventing the deposition of atmospheric moisture on thewarm end of said plunger including a tube of thermally insulatingmaterial projected from said cylinder beyond said packing and towardsaid warm end, said tube being radially spaced from said plunger andshielding 10 said plunger ,irom contact with the atmosphere, a lowpressure packing surrounding said plunger adjacent the warm end of theabove said tube.

a lantern ring surrounding said plunger and located between said highpressure and low pressure packings and vented to atmosphere, said thesame.

11. In a pump for liquefied gases having a cold end including a pumpingcylinder and a warm end including plunger-actuating means: a plungerextending from said cylinder to said actuating means, said plunger beingformed of metal of low heat conductivity and of reduced cross-sectionalarea in at least its outwardly projecting portion,

whereby the flow 01 heat from the warm end to the cold end of saidplunger and the deposition of atmospheric moisture on said warm end arematerially reduced.

CARL R. ANDERSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

' UNITED STATES PATENTS :5 Number Name Date 267,653 Ring Nov. 14, 1882313,180 Colwell Mar. 3, 1885 329,726 'Eilertz Nov. 3, 1885 722,219Fielden Mar. 10, 1903 40 803,260 Wittenmeier Oct. 31, 1905 1,291,983Maisch Jan. 21,- 1919 1,611,159 Buvinger et a] Dec. 21, 1926 1,776,974Henderson Sept. 30, 1930 1,861,132 Parsons May 31, 1932 4 2,292,617 DanaAug. 11, 1942 2,292,634 Hansen Aug. 11, 1942 2,330,781 Langmyhr et al.Sept. 28, 1943 2,348,004 Gruetjen May 2, 1944 so FOREIGN PATENTS NumberCountry Date Great Britain 1919

